We have studied the interaction of cord blood cells with HIV-1. Our studies have demonstrated that monocyte-derived macrophages have increased susceptibility to HIV infection in vitro, in comparison to adult blood monocyte-derived macrophages. We have also studied the effects of cystamine on HIV infection in cord blood monocytes. Cystamine suppressed HIV expression in cord monocytes and macrophages and lymphocytes in a concentration--dependent fashion. These effects are greater than the effects on adult-derived cells. We are currently studying stem cells present in cord monocyte-derived macropages and enriching these cells (CD34+cells).